﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Reflection;
using System.ComponentModel;

namespace Kaiser.Extensions
{
    public enum MappingType
    { 
        PublicProperty=0,
        ByAttributes=1
    }
    public static class ListExtensions
    {
        /// <summary>
        /// 将泛类型集合List类转换成DataTable
        /// </summary>
        /// <param name="list">泛类型集合</param>
        /// <returns></returns>
        public static DataTable ListToDataTable<T>(List<T> entitys)
        {
            //检查实体集合不能为空
            if (entitys == null || entitys.Count < 1)
            {
                throw new Exception("需转换的集合为空");
            }
            //取出第一个实体的所有Propertie
            Type entityType = entitys[0].GetType();
            PropertyInfo[] entityProperties = entityType.GetProperties();

            //生成DataTable的structure
            //生产代码中，应将生成的DataTable结构Cache起来，此处略
            DataTable dt = new DataTable();
            for (int i = 0; i < entityProperties.Length; i++)
            {
                //dt.Columns.Add(entityProperties[i].Name, entityProperties[i].PropertyType);
                dt.Columns.Add(entityProperties[i].Name);
            }
            //将所有entity添加到DataTable中
            foreach (object entity in entitys)
            {
                //检查所有的的实体都为同一类型
                if (entity.GetType() != entityType)
                {
                    throw new Exception("要转换的集合元素类型不一致");
                }
                object[] entityValues = new object[entityProperties.Length];
                for (int i = 0; i < entityProperties.Length; i++)
                {
                    entityValues[i] = entityProperties[i].GetValue(entity, null);
                }
                dt.Rows.Add(entityValues);
            }
            return dt;
        }


        static StringBuilder _jsonStr;
        /// <summary>
        /// 将List转换为Json字符串 by liubd
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="jsonName"></param>
        /// <param name="il"></param>
        /// <returns></returns>
        public static string ListToJson<T>(string jsonName, List<T> il)
        {
            _jsonStr = new StringBuilder();
            _ListToJson(jsonName, il);
            return _jsonStr.ToString();
        }
        private static void _ListToJson<T>(string jsonName, List<T> il)
        {
            _jsonStr.Append("\"" + jsonName + "\":[");
            if (il.Count > 0)
            {
                for (int i = 0; i < il.Count; i++)
                {
                    var obj = Activator.CreateInstance<T>();
                    var type = obj.GetType();
                    var pis = type.GetProperties();
                    _jsonStr.Append("{");
                    for (var j = 0; j < pis.Length; j++)
                    {
                        if (typeof(List<T>) == pis[j].GetValue(il[i], null).GetType())
                        {
                            _ListToJson(pis[j].Name, (List<T>)pis[j].GetValue(il[i], null));
                        }
                        else
                        {
                            _jsonStr.Append("\"" + pis[j].Name + "\":\"" + pis[j].GetValue(il[i], null) + "\"");
                            if (j < pis.Length - 1)
                            {
                                _jsonStr.Append(",");
                            }
                        }
                    }
                    _jsonStr.Append("}");
                    if (i < il.Count - 1)
                    {
                        _jsonStr.Append(",");
                    }
                }
            }
            _jsonStr.Append("]");
        }

       
    }
}
